Fluid emulsion base potential of shea butter

Abstract

The potential of shea butter (SB) as base for fluid, soap-stabilized emulsion and the stability of such formulations have been studied. Stability features (homogeneity, viscosity) of SB/Liquid paraffin (LP) blends containing 1–50 %w/w of SB at ambient temperature were determined to locate the threshold concentration range for fluid outcome. SB emulsion formulations were prepared from the fluid SB/LP blends by homogenizing each at 1:9 ratio (v/v) with potassium hydroxide (KOH) aqueous solution (0.1, 0.2, 0.4, or 0.6 M concentration, respectively), and with 0.2 M KOH at different mixing ratios (2:8, 3:7, 4:6, or 5:5 v/v), respectively. The physical consistency and stability
characteristics (redispersibility, creaming or breaking) of the formulations were studied at room temperature over 12 weeks. The mean disperse-phase globule size and viscosity of formulation samples stable for ≥8 weeks were determined. SB/LP blends containing 1–20 %w/w SB were pourable liquids; SB separated out as sediment from the fluid blends left to stand for 48 h. Higher concentrations solidified. Fluid emulsions were produced at 0.5–18.0 %w/w SB concentrations, having mean globule size of 4.4–43.1 μm and viscosity of 153–1863 cP. The graded KOH concentrations gave emulsion products with different levels of stability. While some were unstable (broken, immobile) in storage, those formulated with 0.1 M KOH (153–354 cP viscosity) remained stable liquids throughout the 12 weeks of study. The best (most stable) formulation contained 4.5 %w/w SB emulsified with 0.2 M KOH.

Keywords: Shea butter; Emulsion base; Fluid; Formulation